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ECAE provides a capability for achieving substantial grain refinement in metallic alloys and thereby producing materials having ultrafine grain sizes in the submicrometer or nanometer range [4].
ECAE processes achieve grain refinement through the introduction of severe plastic deformation.
Significant grain refinement has been demonstrated in a variety of magnesium alloys.
The hardness of the ECAE treated specimens with and without laser melting treatment increase with the increase of pass number.
The friction coefficients of the specimens with only ECAE and with laser melting treatment decrease with increasing pass number.

Introduction The key aspect of semisolid forming technology is preparation of semisolid alloy feedstock with fine spheroidal grains.
On the other hand, some nuclei will be remelted by superheated melt with only a small number of nuclei surviving.
In Fig.3 (b), spheroidal grains are dominant and free of rosettes.
The morphology of Fig.3 (c) comprises a large number of granular grains, a relatively small amount of rosettes and short rodlike arms.
Consequently the number of primary phase is more than that gained at a smaller reversed cone angle under the same pouring temperature.

The 2-d level mesodeformations are determined inside the polycrystalline grains (5-10 micrometers).
The grain boundaries were determined by etching in a standard acid solution (Aqua Regia).
The average grain size defined by the random linear intercept method was equal to 0.120 mm.
The grains are uniaxial.
The number of grains within a cell of the grid is 82 Fig. 1.

• Zone-3 consists of equiaxed grains with a bright surface and recrystallized bulk grain structure.
As the energy and flux of the impinging ions increase, atomic displacements produced in the collision cascades result in an increasing number of residual interstitials and vacancies.
For the "off-axis" PLD films the larger average grain size of about 12 nm indicates different conditions of the grain growth.
Both the C and N atoms in the fcc TiN lattice have a coordination number of 6.
Total substitution of Ti atoms is impossible in the fcc TiN lattice due to different coordination numbers of Al (4) and Ti (6).

The initial average grain size of the material was found to be 50 µm.
After the first pass average grain size reduces to 6 µm and grains are randomly distributed and some are elongated.
After second pass (route Bc) grain size reduced further and lamellar grains of 2 µm spacing were observed.
The material compressed in x direction after 3rd pass of ECAP shows elongated grains with higher density of dislocations, both inside the grains as well as near the grain boundaries.
As depicted in the Fig.9a.with increasing number of passes stage IV hardening tends to become narrower.

As shown in Fig. 5: austenite dominates the microstructure of Co-base alloy surfacing layer, a large number of cell grain structure can be seen clearly from the microscopic morphology.
Under the effect of electromagnetic, grain of surfacing layer organization more refine than not applying to magnetic field, when magnetic field current is I=3A, the refinement of grain achieve to the best state, and distribute uniformly.
Grain is refined by electromagnetic mixing mainly through the three ways to increase the nucleation rate under the effect of the magnetic field [3]: 1) dendrite fragments of the tail of molten pool; 2) separation of semi-molten grain in molten pool edge; 3) heterogeneous nucleation particles.
So, the growth time of dendritic crystal grain along the maximum heat reverse direction is very short, thus the size of grain is reduced.
Cobalt-based surfacing layer is mainly composed of matrix Co, cobalt carbide CoCx and carbide hard phase Cr7C3; In addition, there are a small number of Fe3C.

The present study was aimed to fit Eq. 2 directly to experimental data to deduce the activation energy for various kinds of hydrogen traps including dislocation and grain boundary, incoherent and coherent titanium carbides in steels.
A number of TiC particles of about 20nm in diameter along with a small part of coarser particles can be observed in ferrite matrix (Fig. 1(a)).
The activation energy for grain boundary and dislocation is reasonable because the activation energies for hydrogen desorption from grain boundary and dislocation in pure iron are 17-20 kJ/mol and 26-27 kJ/mol, respectively [1,5,6] and alloying elements may change these values.
The activation energy for hydrogen desorption from coherent TiC precipitate is much higher than that for grain boundary and dislocation but is lower than that for incoherent TiC particle.
Grain boundary and dislocation showed an activation energy of 21.9kJ/mol in Steel A.

Epitaxial growth of the grains from a given layer on the grains formed during the solidification of the previous layer may also occur [3-7].
The resulting microstructure hence exhibit elongated grains that are roughly parallel to the building direction.
Fully austenitic grains can be identified from the EBSD map (Fig. 4(b)).
These grains are elongated following the building direction.
On the one hand, the occurrence of epitaxial growth of the grains from a given layer on top of the previously solidified layer led to a microstructure characterised by elongated austenitic grains roughly parallel to the building direction oz.

Energy spectrum analysis for grain boundary and intracrystalline of liquid forging indicates that: liquid forging has micro-segregation, mainly Cu, Fe, Mg and Mn such elements in the form of compounds gathered at the grain boundaries, resulting in a grain and grain boundary ingredient uneven, where Cu and Fe segregation is especially remarkable.
The compounds band width is much thinner and the numbers much less in the part shape under the pressure of 90Mpa than that of pressure 80Mpa.
Thus, the segregation extent in the liquid die forging part shape under the pressure of 90MPa is lower than that of 80Mpa part, the grain also significantly more fine.
It can be obvious observed from the high and low organization figure that: liquid forging can forming flange blanks without shrinkage, porosity, loose and other casting defect; And improved the organization, refined the grain.
The latter is under the action of the pressure, the crystallization hard shell of the liquid metal or liquid forging part and cavity wall close contact and improve heat exchange between liquid metal and concave die, accelerate the solidification of the liquid forging parts, and because the effects of pressure increased the crystallization point of metal, increases the degree of supercooling, improve the nucleation rate, plus the dendrite crushing and fall off, the nucleation number also greatly increase, thus refined the grain, which has obvious grain refinement for thin liquid forgings.

Size of former austenite grains conforms scale ranges № 5, 6.
While raising nickel content up to 0.33 – 0.54% austenite grain size didn’t change.
Sample number The contamination by nonmetallic inclusions, raiting Size of austenite gaine, raiting Size of martensite needles, mcm non-deformable silicates (fragile) Oxides spot 1 2b, 2a, 3a 1a 5, 6 7-10 2 1b, 2b, 3a 1a 5, 6 4-8 3 2b, 3a 1 a 5, 6 5-8 4 2b, 3а (1b) 1 а 6, 5 2-5 5 1b, 2b, 3a 1 a 6, 5 2-5 6 1б, 2b, 2a 1 a, 2a 6 2-4 7 1b, 2b, 3a 1 a 6 2-5 8 1b, 2b, 3a 1 a 6 2-4 Increasing the content of nickel up to 0.65% (sample №4) greatly grinds martensite needles, and reduce size of former austenite grains.
Size of former austenite grain conforms №6.
Per the results of calculations obtained dependencies, the adequacy of which was checked by actual values in index of the average approximation error: , (1) m - the number of observations; – calculated value of resulted index; – real value of resulted index.